- Note that Homebrew Cask issues should be filed elsewhere.
- Make `brew`/homebrew-core issue differential in simpler language
- Tell people to fix all `brew doctor` issues
- Refer to the issue checklist and make it even more clear and prominent
  that we may close it out immediately if they don't use it.
- Note that proposed new issues should be widely relevant.
- Don't tell people they need to `brew cask install java`; we handle
  this in most places with a Java requirement and probably want issues
  filed where we don't.
- Remove reference to Homebrew Dupes and replace with reference to
  Homebrew Cask to try and get people filing stuff there instead.

Fixes #2608

Be clearer about what's expected and where to file things.

- Note issues may be closed without comment if sufficient information is
  not provided.
- Deprecate Homebrew/brew-evolution, note new feature request flow
- Note some issues should be created on Homebrew/brew

Always a good idea to quote command substitution.

Indicate that feature requests should go there rather than here.

The current one returns a 404.

Closes Homebrew/homebrew#49353.

Signed-off-by: Dominyk Tiller <dominyktiller@gmail.com>

Sadly, relative URLs don't work in this context.

Always leave a blank line between headings and the following checklists.

Closes Homebrew/homebrew#41321.